package com.tjetc.hw;

import java.util.Scanner;

public class 数列求和 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        int m=1;
        double sum=0;
        while (m<=n){
            sum+=(double)Math.pow(-1,m-1)/(2*m-1);
            System.out.println(sum);
            m++;
        }
        System.out.printf("%.6f",sum);
    }
}
